Torsion springs are used as a biasing means for regulating a movable member at a first position and at a second position relative to a base member. For example, JPH08(1996)-121517A discloses a torsion spring assembling construction including a movable member having an engaging hole configured to be engaged with a first end of a torsion spring, a base member having a click hole configured to be engaged with a second end of the torsion spring, and an axis for pivotally supporting the movable member relative to the base member. With the construction of JPH08(1996)-121517A, while the first end of the torsion spring is engaged with the engaging hole, the second end of the torsion spring is assembled to a communication hole in communication with the click hole at non-compressed state. By rotating the movable member at the foregoing state, the second end of the torsion spring is moved from the communication hole to the click hole to set the torsion spring at a predetermined state.
Notwithstanding, with the construction of JPH08(1996)-121517A, because the torsion spring is provided outside the rotation range of the movable member, the base member is required to be provided with a long hole including the click hole and the communication hole engaged with the second end of the torsion spring at the outside of the rotation range of the movable member, which increases the required space for the assembly.
A need thus exists for a torsion spring assembling construction with smaller construction.